1. Field
The present embodiments relate to an organic light emitting display apparatus, and more particularly, to an organic light emitting display apparatus having a thin film encapsulation layer of an improved structure and a method of manufacturing the organic light emitting display apparatus.
2. Description of the Related Technology
In general, an organic light emitting display apparatus includes a display unit having a structure in which a light emission layer formed of an organic material is disposed between an anode electrode and a cathode electrode. When voltages that are different from each other are applied respectively to the anode electrode and the cathode electrode, holes injected from the anode electrode and electrons injected from the cathode electrode recombine in the light emission layer to generate excitons, and when the excitons enter a ground state from an excited state, light emission occurs and images are displayed.
In addition, if the light emission layer of the display unit is exposed directly to moisture, light emitting characteristics easily degrade, and thus, to address the above problem, an encapsulation layer covers the light emission layer. Recently, a thin film encapsulation layer in which organic layers and inorganic layers are alternately stacked has been mainly used.
Here, the inorganic layers prevent moisture from infiltrating into the display unit, and the organic layers mainly serve to grant the thin film encapsulation layer flexibility or planarize the thin film encapsulation layer, rather than the moisture infiltration prevention. The organic layers are not able to prevent the moisture infiltration actually. Therefore, if the organic layers are connected to a moisture source on an outside of the thin film encapsulation layer, the external moisture may infiltrate in the display unit via the organic layers, thereby deteriorating the light emission layer.
Meanwhile, various metal wires including wires for protective circuit that blocks static electricity are provided on an outer portion of the display unit in the organic light emitting display apparatus. However, when forming a thin film encapsulation layer, the organic layers in the thin film encapsulation layer generally cover some parts of the metal wires disposed on the outer portion of the display unit. Then, a moisture infiltration path through which the moisture may infiltrate from outside into the display unit is formed, thereby affecting life span of the organic light emitting display apparatus. The external moisture may be induced through side surfaces of the metal wires having poor step coverage, and then, the moisture may be induced to the organic layers of the thin film encapsulation layer that covers the metal wires. Thus, it seems like a path through which the moisture is induced to the display unit is formed in the organic layers.
Otherwise, an organic layer may cover the metal wires, the thin film encapsulation layer may cover the metal wires and the organic layer, and a first organic layer in the thin film encapsulation layer may directly contact the organic layer. In this case, the external moisture infiltrates through the organic layer covering the metal wires, and the moisture infiltrates to the display unit via the first organic layer in the thin film encapsulation layer, thereby damaging the organic light emitting display apparatus.
Otherwise, if the organic layers in the thin film encapsulation layer cover the metal wires, the organic layers in a liquid phase may extend to outside along side surfaces of the metal wires, before hardening the organic layers. In this case, if the inorganic layers of the thin film encapsulation layer cannot cover the extended portions of the organic layers, the external moisture may infiltrate to the display unit via the extended portions of the organic layers, thereby damaging the organic light emitting display apparatus.
As described above, if the moisture infiltration path is formed, degradation of the display unit is accelerated, and the lifespan of the organic light emitting display apparatus reduces greatly. Thus, effective countermeasures to address the above described problems are necessary.